Phosphate Porous Coatings Enriched with Selected
Elements via PEO Treatment on Titanium and Its Alloys: A Review
Krzysztof Rokosz, Tadeusz Hryniewicz, Łukasz Dudek
Materials 2020, 13(2468); doi:10.3390/ma13112468
Abstract:This paper shows that the subject of porous coatings fabrication by Plasma Electrolytic Oxidation (PEO), known also as Micro Arc Oxidation (MAO), is still current, inter alia because metals and alloys, which can be treated by the PEO method, for example, titanium, niobium, tantalum and their alloys, are increasingly available for sale. On the international market, apart from scientific works/activity developed at universities, scientific research on the PEO coatings is also underway in companies such as Keronite (Great Britain), Magoxid-Coat (Germany), Mofratech (France), Machaon (Russia), as well as CeraFuse, Tagnite, Microplasmic (USA). In addition, it should be noted that the development of the space industry and implantology will force the production of trouble-free micro- and macro-machines with very high durability. Another aspect in favor of this technique is the rate of part treatment, which does not exceed several dozen minutes, and usually only lasts a few minutes. Another advantage is functionalization of fabricated surface through thermal or hydrothermal modification of fabricated coatings, or other methods (Physical vapor deposition (PVD), chemical vapor deposition (CVD), sol-gel), including also reoxidation by PEO treatment in another electrolyte. In the following chapters, coatings obtained both in aqueous solutions and electrolytes based on orthophosphoric acid will be presented; therein, dependent on the PEO treatment and the electrolyte used, they are characterized by different properties associated with their subsequent use. The possibilities for using coatings produced by means of plasma electrolytic oxidation are very wide, beginning from various types of catalysts, gas sensors, to biocompatible and antibacterial coatings, as well as hard wear coatings used in machine parts, among others, used in the aviation and aerospace industries.
Phosphate Coatings Enriched with Copperon Titanium Substrate Fabricated via DC-PEO Process
Krzysztof Rokosz, Tadeusz Hryniewicz, Wojciech Kacalak, Katarzyna Tandecka, Steinar Raaen, Sofia Gaiaschi, Patrick Chapon, Winfried Malorny, Dalibor Matýsek, Kornel Pietrzak, Łukasz Dudek
Materials 2020, 13(1295); doi:10.3390/ma13061295
Abstract: The present paper covers possible ways to fabricate advanced porous coatings enriched in copper on a titanium substrate through plasma electrolytic oxidation (DC-PEO) with voltage control, in electrolytes made of concentrated orthophosphoric acid with the addition of copper(II) nitrate(V) trihydrate. In these studies, solutions containing from 0 to 650 g salt per 1 dm3 of acid and anodic voltages from 450 V up to 650 V were used. The obtained coatings were featuring variable porosity that could be best defined by the 3D parameter Sz which lies in the range 9.72 to 45.18 μm. The use of copper(II) nitrate(V) trihydrate in the electrolyte, resulted for all cases in the incorporation of the two oxidation forms, i.e. Cu+ and Cu2+ into the coatings. Detailed XPS studies layers allowed to state that the percentage of copper in the surface layer of the obtained coatings was in the range of 0.24 at% to 2.59 at%. The XRD studies showed presence of copper (α-Cu2P2O7, and Cu3(PO4)2) and titanium (TiO2-anatase,TiO3, TiP2O7, and Ti0.73O0.91) compounds in coatings. From EDS and XPS studies it was found that the Cu/P ratio rises with the increase of voltage and the amount of salt in the electrolyte. The depth profile analysis by GDOES method showed that the fabricated coatings may be described by a three-layer model consisting of a top porous layer, a semi-porous layer, and a transient/barrier layer.
Porous Coatings Containing Copper and Phosphorus Obtained by Plasma Electrolytic Oxidation of Titanium
Krzysztof Rokosz, Tadeusz Hryniewicz, Wojciech Kacalak, Katarzyna Tandecka, Steinar Raaen, Sofia Gaiaschi, Patrick Chapon, Winfried Malorny, Dalibor Matýsek, Ewa Czerwińska, Anna Iwanek, Kornel Pietrzak, Łukasz Dudek
Materials 2020, 13(828); doi:10.3390/ma13040828
Abstract: To fabricate porous copper coatings on titanium, we used the process of plasma electrolytic oxidation (PEO), with voltage control. For all experiments, the three-phase step-up transformer with the six-diode Graetz bridge, was used. The voltage and the amount of salt used in the electrolyte were determined so to obtain porous coatings. In the framework of this study, the PEO process was carried out at a voltage (450 VRMS), but in four electrolytes containing the salt as copper(II) nitrate(V) trihydrate. Moreover, we showed that the content of salt in the electrolyte necessary to obtain a porous PEO coating was in the range 300–600 g/dm3. After exceeding this amount of salts in the electrolyte, some inclusions on the sample surface were observed. It is worth noting that this limitation of the amount of salts in the electrolyte was not connected with the maximum solubility of copper(II) nitrate(V) trihydrate in the concentrated (85%) orthophosphoric acid. To characterize the obtained coatings, numerous techniques were used. In this work, the scanning electron microscope (SEM) coupled with a dispersion analyzer of X-ray energy (EDS), the surface analysis using the confocal laser scanning microscopy (CLSM), the studies of chemical composition of the surface layer of the obtained coatings by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), glow discharge of optical emission spectroscopy (GDOES), and the biological tests, were used. It was found out that the higher concentration of Cu(NO3)2∙3H2O in electrolyte, the higher roughness of the coatings, which may be described by 3D roughness parameters, such as Sa (1.17–1.90 μm) and Sp (7.62–13.91 μm). The thicknesses of PEO coatings obtained in electrolyte with 300–600 g/dm3 Cu(NO3) 2∙3H2O were in the range from 7.8 μm up to 10 μm. The Cu/P ratio of the whole volume of coating measured by EDS was in the range 0.05–0.12, while for the top layer (XPS) was 0.17–0.24. The atomic concentration of copper (0.54–0.72 at% ) resulted in antibacterial and fungicidal properties of fabricated coatings, what can dedicate them to biocompatible applications.
Fabrication and Characterisation of Porous Coatings Enriched with Copper on CP Titanium Grade 2 under Plasma Electrolytic Oxidation
Krzysztof Rokosz, Tadeusz Hryniewicz, Sofia Gaiaschi, Patrick Chapon, Steinar Raaen, Łukasz Dudek, Winfried Malorny
Technical Gazette 26, 1(2019), 128-134; doi:10.17559/TV-20180124091009
Abstract: In the present paper, coatings obtained on CP Titanium Grade 2 samples by Plasma Electrolytic Oxidation (PEO) in electrolyte containing concentrated phosphoric acid H3PO4 with copper nitrate Cu(NO3)2∙3H2O, are studied with Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X-Ray Photoelectron Spectroscopy (XPS) and Glow Discharge Optical Emission Spectroscopy (GDOES). A three-layer model is proposed on the basis of GDOES depth profile signals and their first and second derivatives. It was found that the time of Plasma Electrolytic Oxidation process has an influence on the chemical composition and the thickness of the obtained porous coatings. The longer time the PEO treatment is applied, the thinner porous coatings are obtained and the lowest amounts of copper, phosphorus and oxygen inside them are found. The proposed model of PEO coatings consists of three layers, i.e. the top one „A”, having a thickness corresponding to the sputtering time in GDOES of about 100 s; the operating conditions applied provide very porous and contaminated by organic substances layer down to about 50 s by sputtering time; the semi-porous sub-layer named „B” has a thickness that depends on the PEO treatment time. The sub-layer „B” of PEO coating is the thickest after one-minute PEO treatment and it decreases with increasing the treatment time. The PEO coating thickness also decreases after each successive PEO processing. The last layer (from the top surface), is the transition sub-layer named „C”, and it has a thickness corresponding to a sputtering time equaling 450 s.
Metal Ions Supported Porous Coatings
by Using AC Plasma Electrolytic Oxidation Processing
Krzysztof Rokosz, Tadeusz Hryniewicz, Steinar Raaen, Sofia Gaiaschi, Patrick Chapon, Dalibor Matýsek, Kornel Pietrzak, Monika Szymańska, Łukasz Dudek
Materials 2020, 13(3838); doi:10.3390/ma1317383
Coatings enriched with zinc and copper as well as calcium or magnesium, fabricated on titanium substrate by Plasma Electrolytic Oxidation (PEO) under AC conditions (two cathodic voltages, i.e., −35 or −135 V, and anodic voltage of +400 V), were investigated. In all experiments, the electrolytes were based on concentrated orthophosphoric acid (85 wt%) and zinc, copper, calcium and/or magnesium nitrates. It was found that the introduced calcium and magnesium were in the ranges 5.0–5.4 at% and 5.6–6.5 at%, respectively, while the zinc and copper amounts were in the range of 0.3–0.6 at%. Additionally, it was noted that the metals of the block S (Ca and Mg) could be incorporated into the structure about 13 times more than metals of the transition group (Zn and Cu). The incorporated metals (from the electrolyte) into the top-layer of PEO phosphate coatings were on their first (Cu+) or second (Cu2+ , Ca2+ and Mg2+ oxidation states. The crystalline phases (TiO and Ti3O) were detected only in coatings fabricated at cathodic voltage of −135 V. It has also been pointed that fabricated porous calcium–phosphate coatings enriched with biocompatible magnesium as well as with antibacterial zinc and copper are dedicated mainly to medical applications. However, their use for other applications (e.g., catalysis and photocatalysis) after additional functionalizations is not excluded.
Novel Porous Phosphorus–Calcium–Magnesium Coatings on Titanium with Copper or Zinc Obtained by DC Plasma Electrolytic Oxidation: Fabrication and Characterization
Krzysztof Rokosz, Tadeusz Hryniewicz, Steinar Raaen, Sofia Gaiaschi, Patrick Chapon, Dalibor Matýsek, Kornel Pietrzak, Monika Szymańska, Łukasz Dudek
Materials 2020, 13(3838); doi:10.3390/ma1317383
Abstract:In this paper, the characteristics of new porous coatings fabricated at three voltages in electrolytes based on H3PO4 with calcium nitrate tetrahydrate, magnesium nitrate hexahydrate, and copper(II) nitrate trihydrate are presented. The SEM, energy dispersive spectroscopy (EDS), glow discharge optical emission spectroscopy (GDOES), X-ray photoelectron spectroscopy (XPS), and XRD techniques for coating identification were used. It was found that the higher the plasma electrolytic oxidation (PEO) (micro arc oxidation (MAO)) voltage, the thicker the porous coating with higher amounts of built-in elements coming from the electrolyte and more amorphous phase with signals from crystalline Ca(H2PO4)2·H2O and/or Ti(HPO4)2·H2O. Additionally, the external parts of the obtained porous coatings formed on titanium consisted mainly of Ti4+, Ca2+, Mg2+ and (PO4)3-, (HPO4)2-, H2PO4-, (P2O7)4- as well as Zn2+ or copper Cu+/Cu2+. The surface should be characterized by high biocompatibility, due to the presence of structures based on calcium and phosphates, and have bactericidal properties, due to the presence of zinc and copper ions. Furthermore, the addition of magnesium ions should accelerate the healing of postoperative wounds, which could lead to faster patient recovery.
Characterization of Porous Phosphate Coatings Enriched with Magnesium or Zinc on CP Titanium Grade 2 under DC Plasma Electrolytic Oxidation
Krzysztof Rokosz, Tadeusz Hryniewicz, Sofia Gaiaschi, Patrick Chapon, Steinar Raaen,
Kornel Pietrzak, Winfried Malorny, João Salvador Fernandes
Metals 2018, 8(112); doi:10.3390/met8020112
Abstract: The aim of the paper is to study and determine the effect of voltage increasing from 500 up to 650 VDC on chemical and electrochemical properties of the obtained porous coatings with plasma electrolytic oxidation (PEO) processes, known also as micro arc oxidation (MAO). In the present paper, the chemical and electrochemical characterization of porous phosphate coatings enriched with magnesium or zinc on commercially pure (CP) Titanium Grade 2 under DC-PEO obtained in electrolytes based on concentrated 85% analytically pure H3PO4 (98 g/mole) acid with additions of 500 g/L of zinc nitrate Zn(NO3)26H2O or magnesium nitrate Mg(NO3)26H2O, are described. These materials were characterized using scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and glow discharge optical emission spectroscopy (GDOES). It was found that the voltage of PEO process has influence on the chemical composition and thickness of the obtained porous coatings as well as on their electrochemical behavior. The higher the potential of PEO treatment, the higher the amount of zinc-to-phosphorus ratio for zinc enriched coatings was obtained, whereas in magnesium enriched coatings, the average amount of magnesium detected in PEO coating is approximately independent of the PEO voltages. Based on XPS studies, it was found out that most likely the top 10 nm of porous coatings is constructed of titanium (Ti4+), magnesium (Mg2+), zinc (Zn2+), and phosphates PO4- and/or HPO42- and/or H2PO4-; and/or P2O74-. On the basis of GDOES studies, a four-sub-layer model of PEO coatings is proposed. Analysis of the potentiodynamic corrosion curves allowed to conclude that the best electrochemical repeatability was noted for magnesium and zinc enriched coatings obtained at 575 VDC.
Characterization of Porous Phosphate Coatings Enriched with Calcium, Magnesium, Zinc and Copper Created on CP Titanium Grade 2 by Plasma Electrolytic Oxidation
Krzysztof Rokosz, Tadeusz Hryniewicz, Wojciech Kacalak, Katarzyna Tandecka, Steinar Raaen, Sofia Gaiaschi, Patrick Chapon, Winfried Malorny, Łukasz Dudek, Kornel Pietrzak,
Metals 2018, 8(411); doi:10.3390/met8060411
Abstract: The aim of the paper is to study and determine the effect of voltage increasing from 500 up to 650 VDC on chemical and electrochemical properties of the obtained porous coatings with plasma electrolytic oxidation (PEO) processes, known also as micro arc oxidation (MAO). In the present paper, the chemical and electrochemical characterization of porous phosphate coatings enriched with magnesium or zinc on commercially pure (CP) Titanium Grade 2 under DC-PEO obtained in electrolytes based on concentrated 85% analytically pure H3PO4 (98 g/mole) acid with additions of 500 g/L of zinc nitrate Zn(NO3)26H2O or magnesium nitrate Mg(NO3)26H2O, are described. These materials were characterized using scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and glow discharge optical emission spectroscopy (GDOES). It was found that the voltage of PEO process has influence on the chemical composition and thickness of the obtained porous coatings as well as on their electrochemical behavior. The higher the potential of PEO treatment, the higher the amount of zinc-to-phosphorus ratio for zinc enriched coatings was obtained, whereas in magnesium enriched coatings, the average amount of magnesium detected in PEO coating is approximately independent of the PEO voltages. Based on XPS studies, it was found out that most likely the top 10 nm of porous coatings is constructed of titanium (Ti4+), magnesium (Mg2+), zinc (Zn2+), and phosphates PO4- and/or HPO42- and/or H2PO4- and/or P2O74-. On the basis of GDOES studies, a four-sub-layer model of PEO coatings is proposed. Analysis of the potentiodynamic corrosion curves allowed to conclude that the best electrochemical repeatability was noted for magnesium and zinc enriched coatings obtained at 575 VDC.
FABRICATION AND CHARACTERISATION OF POROUS, CALCIUM ENRICHED COATINGS ON TITANIUM AFTER PLASMA ELECTROLYTIC OXIDATION UNDER DC REGIME
Krzysztof Rokosz, Tadeusz Hryniewicz, Kornel Pietrzak, Paweł Sadlak, Jan Valicek
Advances in Materials Science, 2017, 17/4 (54), doi:10.1515/adms‐2017‐0021
Abstract:The purpose of this work is to produce and characterize (chemical composition and roughness parameters) porous coatings enriched in calcium and phosphorus on the titanium (CP Titanium Grade 2) by plasma electrolytic oxidation. As an electrolyte, a mixture of phosphoric acid H3PO4 and calcium nitrate Ca(NO3)2·4H2O was used. Based on obtained EDS and roughness results of PEO coatings, the effect of PEO voltages on the chemical com-position and surface roughness of porous coatings was determined. With voltage increasing from 450 V to 650 V, the calcium in PEO coatings obtained in freshly prepared electrolyte was also found to increase. In addition, the Ca/P ratio increased linearly with voltage increasing according to the formula Ca/P = 0.035·U+0.176 (by wt%) and Ca/P = 0.03·U+0.13 (by at%). It was also noticed that the surface roughness increases with the voltage increasing, what is related.
SEM, EDS, AND XPS CHARACTERIZATION OF COATINGS OBTAINED ON TITANIUM DURING AC PLASMA ELECTROLYTIC PROCESS ENRICHED IN MAGNESIUM
Krzysztof Rokosz, Tadeusz Hryniewicz, Steinar Raaen, Dalibor Matýsek, Łukasz Dudek, Kornel Pietrzak
Advances in Materials Science, 2018, 18/3 (57), 10.1515/adms‐2017‐0042
Abstract: In the paper, the effect of voltage increase (from 500 VDC up to 650 VDC) on the structure and chemical composition of the porous coating on titanium made by Plasma Electrolytic Oxidation is presented. Phosphates-based coatings enriched with calcium,magnesium, zinc, and copper in electrolyte based on 1 L of 85% concentrated H3PO4, with additions of Ca(NO3)24H2O, and Mg(NO3)26H2O, and Zn(NO3)26H2O, and Cu(NO3)23H2O, are described. The morphology and chemical and phase composition are evaluated using SEM, EDS, XRD, XPS, GDOES, and CLSM. Based on these analyses, it was found that PEO coatings are porous and enriched with calcium, magnesium, zinc and copper. They consist mainly of the amorphous phase, which is more visible for higher voltages; this is correlated with an increase in the total PEO coating thickness (the higher the voltage, the thicker the PEO coating). However, for 650 VDC, an amorphous phase and titanium substrate were also recorded, with a signal from Ti2P2O7 crystalline that was not observed for lower voltages. It was also found that all obtained may be divided into three sub-layers, i.e., porous, semiporous, and transitional.
Development of Porous Coatings Enriched with Magnesium and Zinc Obtained by DC Plasma Electrolytic Oxidation
Krzysztof Rokosz, Tadeusz Hryniewicz, Sofia Gaiaschi, Patrick Chapon, Steinar Raaen, Winfried Malorny, Dalibor Matýsek, Kornel Pietrzak,
Micromachines 2018, 9(332); doi:10.3390/mi9070332
Abstract: Coatings with developed surface stereometry, being based on a porous system, may be obtained by plasma electrolytic oxidation, PEO (micro arc oxidation, MAO). In this paper, we present novel porous coatings, which may be used, e.g., in micromachine’s biocompatible sensors’ housing, obtained in electrolytes containing magnesium nitrate hexahydrate Mg(NO3)26H2O and/or zinc nitrate hexahydrate Zn(NO3)26H2O in concentrated phosphoric acid H3PO4 (85% w/w). Complementary techniques are used for coatings’ surface characterization, such as scanning electron microscopy (SEM), for surface imaging as well as for chemical semi-quantitative analysis via energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES), and X-ray powder diffraction (XRD). The results have shown that increasing contents of salts (here, 250 g/L Mg(NO3)26H2O and 250 g/L Zn(NO3)26H2O) in electrolyte result in increasing of Mg/P and Zn/P ratios, as well as coating thickness. It was also found that by increasing the PEO voltage, the Zn/P and Mg/P ratios increase as well. In addition, the analysis of XPS spectra revealed the existence in 10 nm top of coating magnesium (Mg2+), zinc (Zn2+), titanium (Ti4+), and phosphorus compounds (PO43-, or HPO42-, or H2PO4-, or P2O74-).
Characterisation of Calcium- and Phosphorus-Enriched Porous Coatings on CP Titanium Grade 2 Fabricated by Plasma Electrolytic Oxidation
Krzysztof Rokosz, Tadeusz Hryniewicz, Sofia Gaiaschi, Patrick Chapon, Steinar Raaen, Kornel Pietrzak, Winfried Malorny,
Metals 2017, 7(354); doi:10.3390/met7090354
Abstract: In the paper, Scanning Electron Microscopy (SEM), Energy-dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), and Glow Discharge Optical Emission Spectroscopy (GDOES) analyses of calcium- and phosphorus-enriched coatings obtained on commercial purity (CP) Titanium Grade 2 by plasma electrolytic oxidation (PEO), known also as micro arc oxidation (MAO), in electrolytes based on concentrated phosphoric acid with calcium nitrate tetrahydrate, are presented. The preliminary studies were performed in electrolytes containing 10, 300, and 600 g/L of calcium nitrate tetrahydrate, whereas for the main research the solution contained 500 g/L of the same hydrated salt. It was found that non-porous coatings, with very small amounts of calcium and phosphorus in them, were formed in the solution with 10 g/L Ca(NO3)24H2O, whereas the other coatings, fabricated in the consecutive electrolytes containing from 300 up to 650 g/L Ca(NO3)24H2O, were porous. Based on the GDOES data, it was also found that the obtained porous PEO coating may be divided into three sub-layers: the first, top, porous layer was the thinnest; the second, semi-porous layer was about 12 times thicker than the first; and the third, transition sub-layer was about 10 times thicker than the first. Based on the recorded XPS spectra, it was possible to state that the top 10-nm layer of porous PEO coatings included chemical compounds containing titanium (Ti4+), calcium (Ca2+), as well as phosphorus and oxygen (PO43- and/or HPO42- and/or H2PO4-, and/or P2O74-).
Porous PEO coatings on titanium, obtained under DC regime, enriched in magnesium, calcium, zinc, and copper
Krzysztof Rokosz, Tadeusz Hryniewicz, Kornel Pietrzak, Łukasz Dudek
World Scientific News 2018, 94(2) 98-113
Abstract: In the present paper, the analysis of SEM and EDS results of porous and enriched in calcium, magnesium, zinc, copper and phosphorus coatings, obtained during 3-minute treatments performed by Plasma Electrolytic Oxidation (PEO)/Micro Arc Oxidation (MAO) processes on CP Titanium Grade 2, is presented. The PEO process was carried out at DC potentials of 500 VDC, 575 VDC, and 650 VDC in electrolytes containing 125 g Ca(NO3)2·4H2O, and 125 g Mg(NO3)2∙6H2O, and 125 g Zn(NO3)2∙6H2O, and 125 g Cu(NO3)2∙3H2O in 1 L H3PO4. It was found that obtained coatings have pores with different shapes and diameters and/or size/dimentions. The Ca/P, Mg/P, Zn/P, Cu/P, and M/P ratios (M=Ca+Mg+Zn+Cu) were equal to 0.074, 0.046, 0.056, 0.042, and 0.218, respectively. The highest value of each of these ratios was recorded for 650 VDC. It may be concluded that the obtained PEO coatings structures most likely are similar to hydroxyapatite-like structures, in which the Ca2+ may be replaced with Zn2+, Mg2+, Cu2+.
FABRICATION AND CHARACTERISATION OF POROUS COATINGS OBTAINED BY PLASMA ELECTROLYTIC OXIDATION
Krzysztof Rokosz, Tadeusz Hryniewicz, Steinar Raaen, Winfried Malorny
Journal of Mechanical and Energy Engineering, 2017, 1(41), 23-30
Abstract: In the paper, characteristics of porous coatings enriched in copper on pure Titanium and its alloys (NiTi, Ti6Al4V, TNZ, Ti2448) as well as on niobium obtained by Plasma Electrolytic Oxidation (PEO) in electrolyte containing H3PO4 within Cu(NO3)2, are presented. All obtained surfaces of PEO coatings have different shapes and diameters of pores. The binding energies of main peaks for titanium Ti2p3/2, niobium Nb3d5/2, zirconium Zr3d5/2, phosphorus (P2p) and oxygen (O1s) suggest the presence of titanium Ti4+, niobium Nb5+ and zirconium Zrx+ (x≤2) as well as PO43–.
SEM and EDS analysis of enriched in phosphorus and copper coatings fabricated by AC-PEO treatment
Krzysztof Rokosz, Tadeusz Hryniewicz, Kornel Pietrzak, Łukasz Dudek
World Scientific News 2018, 95, 246-259
Abstract: In the present paper, the analysis of SEM and EDS results of porous and enriched in calcium, magnesium, zinc, copper and phosphorus coatings, obtained during 3-minute treatments performed by Plasma Electrolytic Oxidation (PEO)/Micro Arc Oxidation (MAO) processes on CP Titanium Grade 2, is presented. The PEO process was carried out at DC potentials of 500 VDC, 575 VDC, and 650 VDC in electrolytes containing 125 g Ca(NO3)2·4H2O, and 125 g Mg(NO3)2∙6H2O, and 125 g Zn(NO3)2∙6H2O, and 125 g Cu(NO3)2∙3H2O in 1 L H3PO4. It was found that obtained coatings have pores with different shapes and diameters and/or size/dimentions. The Ca/P, Mg/P, Zn/P, Cu/P, and M/P ratios (M=Ca+Mg+Zn+Cu) were equal to 0.074, 0.046, 0.056, 0.042, and 0.218, respectively. The highest value of each of these ratios was recorded for 650 VDC. It may be concluded that the obtained PEO coatings structures most likely are similar to hydroxyapatite-like structures, in which the Ca2+ may be replaced with Zn2+, Mg2+, Cu2+.
SEM and EDS studies of selected porous coatings obtained on titanium by Plasma Electrolytic Oxidation
Krzysztof Rokosz, Tadeusz Hryniewicz, Kornel Pietrzak, Łukasz Dudek, Winfried Malorny
World Scientific News 2017, 70(2), 71-85
Abstract:In present work, SEM and EDS results of porous and enriched in calcium, copper, magnesium and phosphorus coatings, which were obtained during 3-minute treatments of Plasma Electrolytic Oxidation PEO (Micro Arc Oxidation MAO) processes on CP Titanium Grade 2 at two potentials, i.e. 500 VDC and 650 VDC, are presented. It was found that the voltage of that process influences the chemical composition of coatings shapes obtained on titanium in electrolytes containing calcium, copper and magnesium nitrates. The pores shapes of PEO coatings formed on titanium in electrolytes containing calcium, copper and magnesium nitrates are presented, too. In addition, it was also noted that with using of higher voltage (here 650 VDC) of PEO treatments, the higher Ca/P, Cu/P and Mg/P ratios were found than those after treatments at 500 VDC.
SEM and EDS studies of porous coatings enriched in calcium and zinc obtained by PEO with ramp voltage
Krzysztof Rokosz, Tadeusz Hryniewicz, Kornel Pietrzak
World Scientific News 2017, 77(2), 242-255
Abstract: In this work, the SEM and EDS results of porous and enriched in calcium or zinc coatings, which were obtained during 3-minute treatments using Plasma Electrolytic Oxidation (Micro Arc Oxidation) processes on CP Titanium Grade 2 at ramp potentials (linear polarization) from 0 up to 650 VDC in electrolytes containing 500 g Ca(NO3)2∙4H2O and/or 500 g Zn(NO3)2∙6H2O in 1 L H3PO4, are presented. It was found that obtained coatings have pores with different shapes and diameters. The Ca/P and Zn/P ratios by atomic concentration are the same and equal to 0.2, what may suggest hydroxyapatite-like structure (M,Ti)x(PO4)y, where M= {Ca, Zn}.
Development and SEM/EDS characterisation of porous coatings enriched in magnesium and copper obtained on titanium by PEO with ramp voltage
Krzysztof Rokosz, Tadeusz Hryniewicz, Kornel Pietrzak, Łukasz Dudek
World Scientific News 2017, 80, 29-42
Abstract: In the present paper, the SEM and EDS results of porous and enriched in calcium and/or zinc coatings, which were obtained during 3-minute treatments by Plasma Electrolytic Oxidation/ Micro Arc Oxidation processes on CP Titanium Grade 2 at ramp potentials (liner polarization) from 0 up to 650 VDC in electrolytes containing 500 g Mg(NO3)2∙6H2O and/or 500 g Cu(NO3)2∙3H2O in 1 L H3PO4, are reported. It was found that the obtained coatings, dependent on the PEO process conditions, have pores with different shapes and diameters. The Mg/P and Cu/P ratios by atomic concentration are the same and equal to 0.09±0.01 (by wt %) | 0.11±0.01 (by at%) and/or 0.40±0.08 (by wt %) | 0.19±0.04 (by at%), respectively. That may testify the hydroxyapatite-like structures of Mg-Ti-PO43– and/or Cu-Ti-PO43– have been identified to occur.
Synthesis and characterisation of porous, calcium enriched coatings formed on Titanium via Plasma Electrolytic Oxidation
Krzysztof Rokosz, Tadeusz Hryniewicz, Kornel Pietrzak
World Scientific News 2017, 83, 29-444
Abstract: The SEM and EDS study results of porous and calcium enriched coatings obtained via Plasma Electrolytic Oxidation (Micro Arc Oxidation) on the Commercial Purity Titanium Grade 2 samples, at three potentials 450 VDC, 550 VDC, 650 VDC in electrolytes containing 500 g Ca(NO3)2∙4H2O in 1000 mL H3PO4, are presented in the paper. In the same electrolyte three Titanium samples, one after other, were treated, with the PEO processing time equaling 3 minutes after each immersion. Based on SEM and EDS results, it was possible to state that all obtained coatings are porous and their calcium-to-phosphorus (Ca/P) ratio decreases with decreasing PEO voltage. In addition, it was found out that electrolyte aging results in decreasing Ca/P ratio, too.
Characterization of porous coatings obtained via plasma electrolytic oxidation (chapter 5)
Krzysztof Rokosz, Tadeusz Hryniewicz, Antje Schutz, Jan Heeg, Marion Wienecke, Winfried Malorny
Materials for Biomedical Engineering, Bioactive Materials, Properties, and Applications,
book edited by Valentina Grumezescu and Alexandru Mihai Grumezescu
Elsevier, 2019, ISBN: 978-0-12-818431-8; https://doi.org/10.1016/B978-0-12-818431-8.00006-4